The biblical observance of Yom Kippur became more elaborate in the Temples.

Unlike the first day of the seventh month [which became known as Rosh Hashanah], the 10th day has a specific designation and purpose in the Torah, with elaborate rites connected to it:

"Mark, the 10th day of the seventh month is the Day of Atonement. It shall be a sacred occasion for you; you shall practice self-denial, and you shall bring an offering by fire to the Lord; and you shall do no work throughout that day. For it is a Day of Atonement, on which expiation is made on your behalf before the Lord your God... Do no work whatever; it is a law for all time, throughout the generations in all your settlements. It shall be a Sabbath of complete rest for you, and you shall practice self-denial; on the ninth day of the month at evening, from evening to evening, you shall observe this your Sabbath" (Lev. 23:27-32).

The designation of this day is reiterated in Numbers:

"On the 10th of the same seventh month you shall observe a sacred occasion when you shall practice self-denial. You shall do no work" (Num. 29:7).

Self-denial--inui nefesh in Hebrew (literally, afflicting one's soul)--traditionally has been understood to refer to fasting. For the Israelites, this Day of Atonement was therefore a day for fasting and complete cessation of work, observed by individuals in their homes and settlements.

While observed today as a time for individual atonement, the biblical Yom Kippur is primarily a priestly institution:

"The priest who has been anointed and ordained to serve as priest in place of his father shall make expiation. He shall put on the linen vestments, the sacral vestments. He shall purge the inmost Shrine; he shall purge the Tent of Meeting and the altar; and he shall make expiation for the priests and for all the people of the congregation " (Lev. 16:29-33).

Since Yom Kippur rites were performed in the sanctuary by the High Priest, the presence of the common people was not required. Individual observance was merely an accompaniment to the work of the High Priest, who was engaged in "rites of purgation" or "rites of riddance," in the sanctuary.

The Torah emphasizes these rituals of purging or cleansing the sanctuary and the altar, and the priests' atonement for themselves and for the people. Kaparah (atonement) means to cleanse that which has been defiled or contaminated. The sanctuary was a place of holiness and of ritual purity, which was tainted over the years by human beings who entered it in states of ritual impurity. If the sanctuary was to function as a holy place, as the dwelling place of the Holy One, it had to be purged of this impurity.

Rabbi Dr. Reuven Hammer is a former President of the International Rabbinical Assembly, he is one of the founders of the Masorti Movement in Israel and is currently Head of the Masorti Beth Din in Israel.